Neuroleptic Malignant Syndrome

A potentially lethal reaction to drugs affecting dopaminergic transmission. Antipsychotics are the leading cause, but it can also occur with antiemetics, antidepressants, and lithium, or after abruptly stopping a dopamine agonist.

Clinical features

• Hyperthermia
• Extrapyramidal effects — lead-pipe rigidity, bradykinesia/akinesia, dystonia, abnormal movements/postures, dysphagia, tremor
• Autonomic effects — tachycardia, hypertension, labile blood pressure, diaphoresis, tachypnoea
• CNS effects — drowsiness, confusion, coma, mutism, incontinence

Investigations: elevated CK, leukocytosis, low serum iron.

Management

Requires specialised hospital care, sometimes ICU admission:

• Discontinue the causative antipsychotic (or other dopaminergic-affecting drug).
• Monitor vital signs and maintain hydration with IV fluids.
• Actively cool the patient.
• DVT prophylaxis.
• Benzodiazepines may be used.
• Bromocriptine 2.5 mg orally every 8 hours is sometimes given as antidotal therapy, though controlled-trial evidence of benefit is lacking.

Follow-up: a psychiatrist should review the ongoing need for antipsychotic therapy — around 30% of patients develop the syndrome again on rechallenge.